HandBrake · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Check whether the installed interface offers it
HandBrake documents process isolation and simultaneous encodes for supported graphical interfaces and hardware. This is a different question from how many entries can wait in a queue. Inspect the installed interface and version before following a control path from another platform. The existence of a long pending list does not mean those jobs are all processing at once, and a higher simultaneous count does not create additional hardware capacity.
Measure the complete workload
For an original comparison plan, choose two permitted short sources with fixed settings and distinct output names. Record the time until both finish when run sequentially, then compare an applicable concurrent configuration. Keep the source storage and other processing conditions stable. Watch total elapsed batch time, resource pressure and successful completion rather than comparing only the fastest momentary frame rate of one job. Competing work can reduce the rate available to each active encode.
Choose a practical limit from the result
The documentation notes hardware requirements and encoder limits rather than promising an unlimited number of parallel jobs. If concurrency creates failures or offers no useful total time improvement, retain the simpler configuration for that workload. Check both resulting files for the intended duration and tracks before calling the comparison successful. Do not generalise a result from two short hardware encodes to every software encoder, filter chain or long programme. Keep the measured configuration with the result so the decision can be reviewed later.